1,831 research outputs found
A sparsity-based method for fault-tolerant manipulation of a redundant robot
As an important part of the manufacturing industry, redundant robots can undertake heavy and tough tasks, which human operators are difficult to sustain. Such onerous and repetitive industrial manipulations, that is, positioning and carrying, impose heavy burdens on the load bearing for redundancy robots' joints. Under the circumstances of long-term and intense industrial operations, joints of redundant robots are conceivably to fall into functional failure, which may possibly cause abrupt joint lock or freeze at unknown time instants. Therefore, task accuracy by end-effectors tends to diminish considerably and gradually because of broken-down joints. In this paper, a sparsity-based method for fault-tolerant motion planning of redundant robots is provided for the first time. The developed fault-tolerant redundancy resolution approach is defined as L1-norm based optimization with immediate variables involved to avoid discontinuity in the dynamic solution process. Meanwhile, those potential faulty joint(s) can be located by the designed fault observer with the proposed fault-diagnosis algorithm. The proposed fault-tolerant motion planning method with fault diagnosis is dynamically optimized by resultant primal dual neural networks with provable convergence. Moreover, the sparsity of joint actuation by the proposed method can be enhanced by around 43.87% and 36.51%, respectively, for tracking circle and square paths. Simulation and experimental findings on a redundant robot (KUKA iiwa) prove the efficacy of the developed defect tolerant approach based on sparsity
Remote sensing techology
Presented at Irrigation district sustainability - strategies to meet the challenges: USCID irrigation district specialty conference held on June 3-6, 2009 in Reno, Nevada.Includes bibliographical references.Irrigated agriculture is the largest water user in New Mexico; in southern New Mexico's Lower Rio Grande region, agriculture uses about one million acre-feet of water each year. Previous research has estimated that the average irrigation efficiency in the area is 44%. This relatively low aggregate efficiency indicates a large potential for water savings from agriculture. In order to determine the potential water savings, the amount of water depleted by crop evapotranspiration (ET) in the Mesilla Valley section of the EBID was estimated using satellite information and ground-level measurements to calculate plant consumptive water use on scales ranging from individual farms to the larger watershed. Two areas of potential water savings were evaluated using the satellite-generated consumptive use information: 1) potential water saving at the farm level and 2) potential water saving at the district level. This study found that the majority of farms in the study region were growing crops under deficit irrigation conditions. Therefore, irrigation improvements at the farm-level are likely to increase both yields and water depletion. Potential water savings at the district level were evaluated by comparing the total volume of water diverted for irrigation versus aggregate ET. From the satellite-generated ET data, district-level efficiency was determined to be 55% in 2002 (a full allocation year). Thus, there appears to be a potential for improving district-level efficiency. This can be accomplished by using regional ET depletion values to plan water releases from the reservoir and improve the diversion and distribution within the canal networks
New Mexico pecan production
Presented at Urbanization of irrigated land and water transfers: a USCID water management conference on May 28-31, 2008 in Scottsdale, Arizona.Includes bibliographical references.Pecans are a major agricultural crop in New Mexico. Currently there are approximately 11,000 hectares of pecans in the Elephant Butte Irrigation District, consuming more than one third of the annual diversion. The research presented here provides previously unavailable broad-scale estimates of pecan ET and pecan yield response to water. The data at the foundation of this paper were generated using the Regional ET Estimation Model (REEM) developed at New Mexico State University for agricultural and riparian vegetation (Samani et al. 2005, 2006, 2007). REEM uses remotely sensed satellite data to calculate ET as a residual of the energy balance. This research extends the results of REEM to an analysis of yield response to water in irrigated pecan production in the EBID. The study region is rapidly urbanizing and experiencing growing competition for scarce surface and groundwater supplies. The results of this research provide new insight into pecan water use and yields. This research illustrates the linkages that can be made between remote sensing technology, farm-level water management, and yield outcomes. This research sheds new light on the long-standing practice of deficit irrigation in pecans, the yield and conservation impacts of this practice, as well as water conservation policy implications
Perception about family physicians: results of a survey of patients visiting specialist clinics for treatment
Objective: To study the perceptions about Family Medicine among patients visiting Specialist Physicians for treatment. Methods: A questionnaire based survey was conducted at the Specialist Clinic, Aga Khan University Hospital, Karachi, Pakistan, in June 2004. Trained volunteers administered the questionnaire among patients visiting Specialist Physicians for treatment. Confidentiality was ensured to all patients and written informed consent was taken as part of the ethical requirements for the conduct of the study. SPSS computer software and Microsoft Excel were used for data management. Results: A total of 100 patients visiting the Specialist Clinic were interviewed, of which fifty four (54%) were women and forty six (46%) were men. The mean age was 36.3 years. Twenty four (24%) respondents had graduate education. Being well-mannered, being familiar with a family\u27s medical history and possessing the abilities to conduct proper checkups were quoted as main characteristics of Family Physicians by thirty eight (38%), seventeen (17%) and twenty five (25%) respondents respectively. If they had a chest pain, fifty six (56%), forty three (43%) and one (1%) respondents would consult a Family Physician, Cardiologist and Chest Specialist, respectively. Conclusion: We have documented perceptions regarding family medicine among patient\u27s visiting Specialist Physicians for treatment. It is recommended that programs highlighting role and functions of family medicine should be started for the publi
An evaluation of comprehensiveness, feasibility and acceptability of a fertility awareness educational tool
The World Health Organization (WHO) and World Bank have identified infertility as a global public health issue. Since the 1980s, WHO has advocated for a focus on prevention, especially where the burden of prevalence is highest, specifically in women from low- and middle-income countries (LMIC). The aim of the two studies presented here is to demonstrate a process to enhance implementation efforts in fertility awareness programmes that could assist in preventing some forms of infertility, and increase understanding of factors that could result in fertility problems. The fertility status awareness tool (FertiSTAT) for the Middle East was adapted to provide an illustrative example of requirements for region- or country-specific adaptation. The mixed methods approach used included a survey of international medical experts concerning the comprehensiveness of risks included in the original FertiSTAT (Study I), and stakeholder meetings to assess the feasibility and acceptability of using an adapted FertiSTAT in the Middle East (Study II). The results indicate that the content of the original FertiSTAT was acceptable but not comprehensive in its coverage of potential risk factors; for example, it did not include genital tuberculosis, human immunodeficiency virus, consanguineous relationships and female genital mutilation/cutting. Furthermore, stakeholder meetings revealed that implementation in the Middle East would be enhanced by the use of more culturally sensitive wording. The data highlight the importance of implementation research with participants from LMIC, and the need for standardized protocols for adaptation of any fertility awareness programme or tool before practical application
Program Model Checking: A Practitioner's Guide
Program model checking is a verification technology that uses state-space exploration to evaluate large numbers of potential program executions. Program model checking provides improved coverage over testing by systematically evaluating all possible test inputs and all possible interleavings of threads in a multithreaded system. Model-checking algorithms use several classes of optimizations to reduce the time and memory requirements for analysis, as well as heuristics for meaningful analysis of partial areas of the state space Our goal in this guidebook is to assemble, distill, and demonstrate emerging best practices for applying program model checking. We offer it as a starting point and introduction for those who want to apply model checking to software verification and validation. The guidebook will not discuss any specific tool in great detail, but we provide references for specific tools
Association of Longer Leukocyte Telomere Length With Cardiac Size, Function, and Heart Failure.
IMPORTANCE: Longer leukocyte telomere length (LTL) is associated with a lower risk of adverse cardiovascular outcomes. The extent to which variation in LTL is associated with intermediary cardiovascular phenotypes is unclear. OBJECTIVE: To evaluate the associations between LTL and a diverse set of cardiovascular imaging phenotypes. DESIGN, SETTING, AND PARTICIPANTS: This is a population-based cross-sectional study of UK Biobank participants recruited from 2006 to 2010. LTL was measured using a quantitative polymerase chain reaction method. Cardiovascular measurements were derived from cardiovascular magnetic resonance using machine learning. The median (IQR) duration of follow-up was 12.0 (11.3-12.7) years. The associations of LTL with imaging measurements and incident heart failure (HF) were evaluated by multivariable regression models. Genetic associations between LTL and significantly associated traits were investigated by mendelian randomization. Data were analyzed from January to May 2023. EXPOSURE: LTL. MAIN OUTCOMES AND MEASURES: Cardiovascular imaging traits and HF. RESULTS: Of 40 459 included participants, 19 529 (48.3%) were men, and the mean (SD) age was 55.1 (7.6) years. Longer LTL was independently associated with a pattern of positive cardiac remodeling (higher left ventricular mass, larger global ventricular size and volume, and higher ventricular and atrial stroke volumes) and a lower risk of incident HF (LTL fourth quartile vs first quartile: hazard ratio, 0.86; 95% CI, 0.81-0.91; P = 1.8 × 10-6). Mendelian randomization analysis suggested a potential causal association between LTL and left ventricular mass, global ventricular volume, and left ventricular stroke volume. CONCLUSIONS AND RELEVANCE: In this cross-sectional study, longer LTL was associated with a larger heart with better cardiac function in middle age, which could potentially explain the observed lower risk of incident HF
Shorter leukocyte telomere length is associated with adverse COVID-19 outcomes: A cohort study in UK Biobank
Background Older age is the most powerful risk factor for adverse coronavirus disease-19 (COVID-19) outcomes. It is uncertain whether leucocyte telomere length (LTL), previously proposed as a marker of biological age, is also associated with COVID-19 outcomes.
Methods We associated LTL values obtained from participants recruited into UK Biobank (UKB) during 2006–2010 with adverse COVID-19 outcomes recorded by 30 November 2020, defined as a composite of any of the following: hospital admission, need for critical care, respiratory support, or mortality. Using information on 130 LTL-associated genetic variants, we conducted exploratory Mendelian randomisation (MR) analyses in UKB to evaluate whether observational associations might reflect cause-and-effect relationships.
Findings Of 6775 participants in UKB who tested positive for infection with SARS-CoV-2 in the community, there were 914 (13.5%) with adverse COVID-19 outcomes. The odds ratio (OR) for adverse COVID-19 outcomes was 1·17 (95% CI 1·05–1·30; P = 0·004) per 1-SD shorter usual LTL, after adjustment for age, sex and ethnicity. Similar ORs were observed in analyses that: adjusted for additional risk factors; disaggregated the composite outcome and reduced the scope for selection or collider bias. In MR analyses, the OR for adverse COVID-19 outcomes was directionally concordant but non-significant.
Interpretation Shorter LTL is associated with higher risk of adverse COVID-19 outcomes, independent of several major risk factors for COVID-19 including age. Further data are needed to determine whether this association reflects causality.
Funding UK Medical Research Council, Biotechnology and Biological Sciences Research Council and British Heart Foundation
Evaluation of the neuroprotective effects of electromagnetic fields and coenzyme Q 10 on hippocampal injury in mouse
Electromagnetic fields (EMFs) are reported to interfere with chemical reactions involving free radical production. Coenzyme Q 10 (CoQ10) is a strong antioxidant with some neuroprotective activities. The purpose of this study was to examine and compare the neuroprotective effects of EMF and CoQ10 in a mouse model of hippocampal injury. Hippocampal injury was induced in mature female mice (25–30 g), using an intraperitoneal injection of trimethyltin hydroxide (TMT; 2.5 mg/kg). The experimental groups were exposed to EMF at a frequency of 50 Hz and intensity of 5.9 mT for 7 hr daily over 1 week or treated with CoQ10 (10 mg/kg) for 2 weeks following TMT injection. A Morris water maze apparatus was used to assess learning and spatial memory. Nissl staining and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) tests were also performed for the histopathological analysis of the hippocampus. Antiapoptotic genes were studied, using the Western blot technique. The water maze test showed memory improvement following treatment with CoQ10 and coadministration of CoQ10 + EMF. The Nissl staining and TUNEL tests indicated a decline in necrotic and apoptotic cell count following treatment with CoQ10 and coadministration of CoQ10 + EMF. The Western blot study indicated the upregulation of antiapoptotic genes in treatment with CoQ10, as well as coadministration. Also, treatment with EMF had no significant effects on reducing damage induced by TMT in the hippocampus. According to the results, EMF had no significant neuroprotective effects in comparison with CoQ10 on hippocampal injury in mice. Nevertheless, coadministration of EMF and CoQ10 could improve the neuroprotective effects of CoQ1
Fifteen new risk loci for coronary artery disease highlight arterial-wall-specific mechanisms
Coronary artery disease (CAD) is a leading cause of morbidity and mortality worldwide. Although 58 genomic regions have been associated with CAD thus far, most of the heritability is unexplained, indicating that additional susceptibility loci await identification. An efficient discovery strategy may be larger-scale evaluation of promising associations suggested by genome-wide association studies (GWAS). Hence, we genotyped 56,309 participants using a targeted gene array derived from earlier GWAS results and performed meta-analysis of results with 194,427 participants previously genotyped, totaling 88,192 CAD cases and 162,544 controls. We identified 25 new SNP-CAD associations (P < 5 × 10(-8), in fixed-effects meta-analysis) from 15 genomic regions, including SNPs in or near genes involved in cellular adhesion, leukocyte migration and atherosclerosis (PECAM1, rs1867624), coagulation and inflammation (PROCR, rs867186 (p.Ser219Gly)) and vascular smooth muscle cell differentiation (LMOD1, rs2820315). Correlation of these regions with cell-type-specific gene expression and plasma protein levels sheds light on potential disease mechanisms
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